Slide fastener



' SLIDE FASTENER Filed May 30, 1942 l Home! H,

NVENTOR Hamm,

ATTORNEY ence of even a slight amount Patented Nov. 30, 1943 2,335,668 sum; FA's'rENEn Homer A. Hamm,

1011, Inc., a corporat Meadville, Pa., assignor to Taion of Pennsylvania Application May 30, 1942, Serial No. 445,168 2 Claims. (01. 24-205) My invention relates to slide fasteners which,

In early attempts of pioneer slide fastener man- I ufacturers to put out a commercially acceptable product at a low enough cost, the elements carried by the fabric strips were made from ferrous metals such as soft steel. In view of the fact that these fasteners were intended for use on various leather and fabric articles, principally clothing, the problem of iron rust was soon apparent and various attempts were made to apply finishes to the metal elements to minimize rusting. Because of the extreme seriousness of iron rust when the fasteners were used on clothing and other articles, ferrous metals had to be abandoned before any commercial success was made of slide fasteners. The entire slide fastener industry has been built up, with the exception of plastic fasteners, by the use of metal fastener elements made from non-ferrous alloys, principally copper nickel alloys knowngenerally as nickelsilver, copper zinc alloys similar to brass, and often referred to as gilding metals, and aluminum.

Of course, throughout the period of about twenty-five years of. the commercial industry, it has always been recognized that steel would have very important advantages as a metal for the slide fastener elements because of its much lower cost and high strength.

Recently, because of the scarcity of the nonferrous metals commonly used in the manufacture of slide fasteners, attempts hav been made to manufacture slide fasteners from steel covered with a thin layer of copper. Due to the severe working and cutting up of the metal into the small elements, the copper would not form a complete envelope around the steel core of the metal elements and such fasteners would, nevertheless, rust when in use and consequently soil the fabric tapes or other fabric to which the fastener may be attached. Attempts were made to apply further coatings of such metals as tin over these fasteners after tached to the tape, by dipping them in a metallizing bath, but such expedients only help in minimizing rust and do not make the resulting product nearly so desirable commercially as the fasteners made from non-ferrous alloys. The presof rust stain on the fabric tapes of' the slide fasteners or on garments, especially when made of the lighter shades of material, is highly objectionable. In any consideration of applying fastener elements after they are attached to the tape, there are important limitations because such tapes must not be discolored or have their strength affected in any such processes. Furthermore, any such operation, even if the resulting product were satisfactory, involves increased cost of fastener manufacture.

.It is this major problem of avoiding even slight amounts of iron rust which causes serious stains on fabric while retaining the above stated advantag s of steel, that my invention seeks to solve. In the consideration of various metal articles, any one of many expedients is sufiicient for preventing rusting serious enough to affect the use of the article. which consist of a large number of small metal elements intimately and permanently attached to fabrics of various shades, the problem is of an entirely difierent order.

The problem is even more difficult when it is considered how the great majority of slide fas teners are manufactured. Such manufacture involves the feeding of a preformed continuous metal wire to a machine which cuts the wire up into small pieces and attaches them to the tape. The majority of slide fasteners manufactured at the present time are made by the machine and process substantially as disclosed in Sundback Patent wire of generally Y-shaped cross-section is fed to a shearing knife which slices the fastener member blanks from the end of the wire. These blanks are then die-formed by a punch and die,'transferred to an attaching station and clamped on the edge of a fabric tape. Because of such shearing and forming operations, any plating or coating which might have been applied to the wire before it is fed to the machine, will not result in a fastener product which is completely plated or coated. Thus, if a steel base wire is used even though it be covered with copper, the slide fastener elements after being attached to the tape, will have exposed portions of steel which are liable to rust.

Having regard to the commonly used methods of slide fastener manufacture, the difliculty of protecting the steel elements by any complete envelope of coating material will be apparent.

My invention eliminates the necessity forany plating or coating operation after the fastener the elements were atprotective coatings to the elements are attached to the tape and at the same time, produces a product where the metal elements consist principally of a rustable ferrous metal such as soft steel and which will befree from iron rust throughout the ordinary life of the fastener even to the extent of preventing rust stains on light colored fabric tapes of the fastener. This result is accomplished even though the fastener. elements have exposed portions of steel as a consequence of the proces of manufacture referred to above.

In the practice of my invention the protective coating material is applied to the steel wire before it is cut up and formed into fastener elements. It will be evident that any coating mae0 terial can thus be applied much more economi- I-Iowever, in dealing with slide fasteners No. 1,467,015. In that machine a metal in the fastener-making machine.

cally to such a continuous wire than to a small number of separate fastener elements even though it were possible to apply such coatings to the individual elements.

The surprising results of my invention may be partially explained by the electrolytic theory of rusting, which means that a metal such as iron will be protected from rusting as long as it is in close contact with an easier rusting ,metal higher in the electromotive series. Rusting is here used in its broad sense to mean corrosion of the metal by exposure to weathering or water.

It has been found that a continuous steel wire can be very economically provided with a strongly adherent, dense and uniform coating of pure zinc by a process of electroplating wherein much higher amperage currents are employed than commonly employed in electroplating operations. Of course, I do not mean to exclude from the field of my invention the utilization of any method of applying a protective coating to the steel base material. It is of great advantage to apply the coating to the wire before it is out into the small fastener elements and in so doing it is important that the coating be applied so that it will adhere strongly to the steel throughout th fas-- tener manufacturing operations instead of flaking off. I

Such coating is preferably applied by what is known as the "Bethanizlng process, which results in a deposit of pure virgin zinc upon the surface of the wire. While most fasteners which have been made to date in accordance with my invention have been made from this electrolytic zinc-coated wire, satisfactory results have also been obtained from cadmium-coated wire. It is known that under exposure conditions cadmium acts' in the same manner 'as if it were above iron in the electromotive series Or in other words, itis known as one of the metals which is anodic to iron. While there are several other such metals including aluminum, magnesium and chromium, considerations of cost, availability, adhesion, ductility, etc., point, at least at the present time, to zinc. These metals are sometimes referred to as less noble than iron and while any of them may be employed within the broader aspects of my invention, my discovery indicates that pure electrolytic zinc has peculiar advantages, although, as before stated, cadmium has been employed with quite satisfactory results.

In the practice of my invention, steel wire has been coated in this manner with zinc, with a thickness of about six ten-thousandths of an inch, either before or after rolling to the Y- shaped cross-sectional form employed in commercial operation under the above mentioned Sundback patent, and fasteners made direct y from the plated wire by such machine and process. The resulting fastener has a large number of fastener elements in which the crotch or tape contacting portions, the side surfaces and ends are well covered with zinc, and wherein the zinc coating smears to some extent over the other surfaces which have been sheared and die-formed v There are, nevertheless, bare surfaces of steel remaining upon the fastener elements. When these fasteners have been subjected to tests to determine their ability to resist rust, the results have been astounding. Such fasteners have been wrapped in wet cloth and kept wet for long periods of time without showing an rust stain whatever upon the wet fabric. They have been subjected to considerable wear and wetness without showing any rust stains upon white fabric tapes. They have even been subjected to salt sprays for a considerable time without showing any iron rust stains on white fabric tapes.

Another important advantage is the improved workability of the steel due to the protective coating material. It has been found in actual experience in fastener manufacture that the dies and tools have avery much longer life when operating on the coated wire than when operating on the bare steel wire. The zinc or cadmium, has, in a sense, a lubricating effect on the tools and allows the metal to flow much more freely in the cold working processes required in slide fastener manufacture.

In the accompanying drawing, I have shown a slide fastener manufactured in accordance with one embodiment of my invention. drawing:

Fig. 1 is a perspective view of a short length of fastener stringer;

Fig. 2 is an enlarged sectional view to show one of the fastener elements in detail;

Fig. 3 is a similar view looking at the opposite side of a fastener member;

Fig. 4 is a sectional view taken on line 4-4 of Fig. 3;

Figs. 5 and 6 are cross-sections taken on line 5-5 and 6G, respectlvely,'of Fig. 2; and

Fig. 7 is a perspective view showing a portion of continuous wire from which slide fasteners are manufactured.

Slide fasteners as commonly known in the art, consist principally of two fabric tapes each having a series of fastener elements clamped firmly around the tape edge. At the ends of the rows of fastener elements and also attached to the tapes are suitable stop members and a slider is mounted upon the rows of fastener elements and movable along them to close and open the fastener. The general construction of such slide fasteners is so commonly known that no elaborate illustration and description are necessary.

In the The short length of slide fastener stringer 11-.

lustrated in Fig. 1 shows a number of fastener elements sometimes called scoops, I, attached to the corded edge 8 of a fabric tape 9. Each of these fastener elements consists of a head portion having a projection In on one side and a recess H on the other side, and when the fastener is closed, the projections of the elements on one stringer engage in the recesses of the elements in the mating stringer, as is well known in the art. The elements are held firmly on the tape by arms or jaws I 2 which are clamped around the corded edge 8 in the fastener-making machine. The surfaces l3 and the surfaces I4 may be conveniently referred to as the side and end" surfaces, respectively, and these are the surfaces upon which the slider rides as it moves to open or close the fastener. The inner surfaces I! of the crotch or jaws are in contact with the tape after the fastener elements have been attached. These surfaces l3, l4 and IS in the finished fastener element are substantially the same as the original outer surfaces of the Y- shaped wire as fed to the fastener-making machine. This will be apparent from Fig. 7, showing the plated Y-shaped wire wherein the surfaces 23 correspond to the side surfaces l3 of the fastener elements parallel to the plane of the tape, the surfaces 24 correspond to the surfaces H, and the surfaces 25, to the surfaces ii of the fastener elements.

This illustrative embodiment of my invention this projection as shown in Fig. 3, would quired for fastener art. While the results flowing from my invention are especially good when used in connection. with that machine and process, it will be apparent that my invention is adaptable to fasteners made by other machines and processes.

This coating is indicated by the numeral it and its thickness is considerably exaggerated in the drawing. While the thickness of coating may vary considerably depending on the results desired, it has been found that a zinc coating of about six ten-thousandths of an inch in thickness produces excellent results. The side surfaces it and id perpendicular to the plane of the tape are surfaces which result from shearing across the section of the Y-shaped wire. While there will be a certain amount of the original covering metal smeared over these surfaces in the shearing operation, they will not be completely covered. The line to which the smearing would extend varies considerably and as an example, it might take the form shown by the uneven line it on the surface H, and it on the surface While the surfaces of the recess it may have shght amount of protective metal, it will be comparatively thin and there are considerable areas of exposed steel. Ihe front surface of the projection id as seen in Fig. a, has a rather complete coating 2! although the rear surface S: smeared with the coating to an uneven line, as indicated at 22.

it will thus be seen that the fastener elements have some surfaces fully covered. with the coating and other surfaces which are exposed. How ever, the commercial sizes of slide fastener ele aesaoce If desirable, in order to obtain certain finish effects or to prevent any smudging upon fabric or other things which might be rubbed against the'coating, a light plating of chromium, nickel or bronze may be used. Such plating could be applied over the zinc or cadmium-coated wire before the slide fastener is manufactured, or it may be applied to the fastener elements after they are manufactured from the coated wire and applied to the tape.

As a result of my invention, it will now be clear that the long-felt need in the slide fastener-industry for a non-rusting slide fastener with steel parts, has been filled. The many advantages to the public who use such slide fasteners, from the standpoint of lowered cost of' manufacture, strength, durability and appearance, will be apparent to anyone skilled in the art.

While I have shown and described in this application one embodiment which my invention may assume in practice, this embodiment is merely for the purposes of illustration and description and various forms may be devised within the scope of my invention as defined in the appended claims.

What I claim as my invention is: l. A fastener stringer for slide fasteners comprising a fabric tape and a series of metal fastener elements attached to one edge of the tape in closely spaced relation, each of said elements having jaw portions engaged aroundthe edge of the tape, and an interlocking portion projecting from said tape with a recess formed one of the faces of the element which is perpendicular to ments are such that the distance between any 40 exposed steel and a portion of the protective coating is of the order of one millimeter or less. This is well within the range of protection afforded by th coating material. The outer surfaces against which the slider wears and the front surfaces of the projections Hi, which also get some wear in actual use, are well covered with a coating substantially as thick and dense as the coating applied to the original wire. Thus, the coating will last throughout the normal wear-. ing life of the fastener. which bear against the tape and therefore liable to be subjected to long periods of wetness, are

well covered with the protective coating maferrous metals such as steel and coated with the same material as the fastener elements. The use of this protective coating on these elements would likewise permit of their manufacture from Also, the surfaces It steel base material without any serious effects from rusting due to their close contact with the fabric of the tapes and with the fabrics of the garments.

In the manufacture of slide fasteners according to the above described embodiment of my invention, it has been found that the shearing or cutting tools, the forming punches and dies retener i'r'iembers willihave considerably longer life than when operating upon uncoated steel material or upon steel coated with copper.

and attaching the slide fasv the plane of the tape, and a projection on the side of the element opposite said recess, said elements being made of a rustable ferrous metal; the side surfaces parallel to the plane of the tape, the end surfaces perpendicular to the plane of the tape, and the inner surfaces of the jaws all being substantially uniformly covered with a coating of protecting metal which is anodic to iron, and the side surfaces of said elements which are perpendicular to the plane of the tape including the surfaces of the recess being non-uniformly covered with said protecting metal, whereby the fabric tape is protected against rust stains during normal use of the slide fastener.

2. A fastener stringer for slide fasteners comprising a fabric tape and a series of metal fastener elements attached to one edge of the tape in closely spaced relation, each of said elements having jaw portions engaged around the edge of the tape, and an interlocking portion projecting from said tape with a recess formed in one of the faces of the element which is perpendicular to the plane of the tape, and a projection on the side of the element opposite said recess, said elements being made of rustable steel; the side surfaces. parallel to the plane of the tape, the end surfaces perpendicular to the plane of the tape, and thelnner surfaces of the jaws all being substantially uniformly covered with a coating of zinc, and the side'surfaces of said elements which are perpendicular to the plane of the tape in- I cluding the surfaces ofthe recess being only partially covered with zinc, the exposed steel surfaces being so small that they are protected from iron rust by the proximity of the zinc coating,

'wliereby'the' fabric tape is protected against rust stains during the-normal life of the slide fastener.

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